A variety of methods have heretofore been employed for facilitating testing of selected components and/or input versus output functions of electrical assemblies in a rapid and effective manner. Such methods are commonly employed for quality control, trouble shooting, and for analysis purposes and ordinarily must be done rapidly in order to minimize costs and expenses.
The assemblies commonly include resistors, capacitors and other electrical components of which all or certain selected components must be tested individually and/or in predetermined combinations due to the fact that the components of different assemblies are often arranged differently as well as testing variations of input versus output functions of the entire assembly.
A variety of test fixtures have been developed over past years for testing electrical assemblies. The text fixtures have generally been designed to either test a single assembly or circuit board repetitively or different assemblies according to electrical circuit designs unique to each.
In most cases, the prior-art test fixtures have characteristically featured at least two spaced-apart platens with the assembly mounted on one and a plurality of openings through the other in which electrically conductive probe members are disposed in selected openings corresponding and in registration with the terminal(s) of the assembly or circuit board scheduled to be tested. The probe members are characteristically reciprocally movable relative the openings and at least one of the platens is reciprocally movable towards and away from the other (commonly by application of a vacuum) so as to enable an end of the probe member facing the terminal(s) to make electrical contact therewith. The opposite end of the probe members have characteristically been individually wired directly by electrical conductors to the test device or to an electrical plug which is connected to the test device. Such practice greatly diminishes the universality of the device since the wires must be disconnected in order to arrange a different array of probe members for testing different assemblies or even in some cases for testing different terminals on the same assembly which is costly and time consuming.
Examples of test fixtures that feature such electrical conductor wiring between the probe members and the test device are respectively disclosed in U.S. Pat. Nos. 3,584,300; 4,115,735; 4,344,033; 4,496,903; 4,536,051; 4,544,886; and 4,625,164, the disclosures of which are incorporated herein by reference.
An example of a universal testffixture for which the probe members are not wired directly to the test device is disclosed in U.S. Pat. No. 4,443,756, the disclosure of which is incorporated herein by reference. The test fixture features upper, intermediate, and lower platens with the lower platen provided with a matrix of electrically conductive pads that can be connected in various patterns to the test device according to the terminals of the assembly or circuit board scheduled for testing. The assembly or circuit board to be tested is mounted on the upper platen and probe members are mounted for reciprocal movement through openings through the intermediate platen that are preselected for registration with both particular pads on the bottom platen and terminals scheduled for testing on the assembly mounted in the upper platen. In operation however, the intermediate platen is secured either by vacuum or other means to the lower platen and only the upper platen is reciprocally movable towards and away from the intermediate platen which eliminates a degree of freedom in movement of the lower platen relative the upper platen and consequently diminishes the universality of the test fixture.
Differing types of probe members have been developed over the years for use in test fixtures such as previously described of which but a few examples are disclosed in U.S. Pat. Nos. 4,397,519; 4,633,176; and 4,659,987, the disclosures of which are incorporated herein by reference.
Yet another example of a universal circuit board test fixture is disclosed in U.S. Pat. No. 4,357,062, the disclosure of which is incorporated herein by reference. Although the probe members in this test fixture are not wired to the test device, intermediate rigid pins are employed between the probe members and the terminals to be contacted which greatly increases the complexity of set-up and the time and expense associated therewith.
In contrast to such practice, the present invention provides a universal test fixture that can easily be adapted to test selected components of the same and a variety of different assemblies as well as for analyzing input versus output functions thereof by including an array of probe members that can be selectively employed according to the particular test requirements involved in a simple and economical manner.